TAS-118 Plus Oxaliplatin Potential New Standard Therapy for Advanced Gastric Cancer

Barcelona, Spain—Findings from the phase 3 SOLAR study suggest TAS-118 plus oxaliplatin as a potential new, standard first-line chemotherapy for the treatment of patients with advanced gastric cancer, according to data being presented at the ESMO 21st World Congress on Gastrointestinal Cancer.

“A fluoropyrimidine plus platinum combination has been used as the standard first-line chemotherapy for advanced gastric cancer,” said Yoon-Koo Kang, MD, PhD, Asan Medical Center, Seoul, Republic of Korea during his presentation explaining that TAS-118 is an oral drug containing S-1 that is a fluoropyrimidine preparation combining tegafur, a prodrug of 5-fluorouracil, gimeracil, and oteracil potassium, and leucovorin.

Citing previous study data demonstrating the promising activity of S-1 plus leucovorin and oxaliplatin in patients with advanced gastric cancer, Dr Kang and colleagues conducted the open-label, phase 3 SOLAR trial to evaluate the safety and efficacy of these regimens in patients with advanced gastric cancer in Japan and Korea.

Between January 2015 and December 2016, a total of 711 patients were enrolled in the study and randomized in a 1:1 ratio to receive S-1 40 to 60 mg and leucovorin 25 mg for 7 days and oxaliplatin 85 mg/m2 on day 1 every 2 weeks (TAS-118 plus oxaliplatin; n=356) or S-1 40 to 60 mg for 21 days and cisplatin 60 mg/m2 on day 1 (Korea) or day 8 (Japan) every 5 weeks (SP; n=355).

Ultimately, 11 patients did not receive the protocol treatment and 19 patients from the full analysis set were excluded for ineligibility.

The primary end point of the SOLAR study was overall survival (OS) in the full analysis set, and secondary end points included progression-free survival (PFS), overall response rate (ORR), and safety.

As per the primary analysis (491 events), the median OS was 16.0 months with TAS-118 plus oxaliplatin and 15.1 months in SP (hazard ratio [HR], 0.83; 95% CI, 0.69-0.99; stratified log-rank test P=.039). In addition, the median PFS was 7.1 months versus 6.4 months, respectively (HR, 0.79; 95% CI, 0.66-0.93; P=.005), and the ORR was 73.5% and 50.0%, respectively (P<.001).

Grade ≥3 adverse events occurred in 69.6% and 69.3% of patients in the TAS-118 plus oxaliplatin and SP arms, respectively. Stomatitis, diarrhea, peripheral sensory neuropathy, and weight loss were the most common grade 3/4 adverse events.

There were 2 treatment-related deaths reported in the TAS-118 plus oxaliplatin arm, and no new safety signals observed in either treatment arm.

“In summary, the phase 3 SOLAR study demonstrated better efficacy of TAS-118 plus oxaliplatin compared to S-1 plus cisplatin in advanced gastric cancer, with a better overall survival, PFS, and overall response rate,” said Dr Kang.

“We can conclude that TAS-118 plus oxaliplatin can be a new standard first-line regimen for the treatment of advanced gastric cancer,” he concluded.—Hina Khaliq

Kang Y, Chin K, Chung H, et al. A phase III study of TAS-118 plus oxaliplatin versus S-1 plus cisplatin as first-line chemotherapy in patients with advanced gastric cancer (SOLAR study). Presented at: the ESMO 21st World Congress on Gastrointestinal Cancer; July 3-6, 2019; Barcelona, Spain. Abstract LBA-003.